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932 Pathophysiology > Respiratory physiology > Flashcards

Respiratory physiology Flashcards

1
Q

The purpose of the pulmonary system is to:

A 
supply oxygen from the atmosphere to the blood while removing CO2
help maintain acid-base balance
allow for phonation
provide for pulmonary defense
provide oxygen for metabolism
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2
Q

Partial pressure of gases in the air include:

A

nitrogen: 78%
oxygen: 21%
CO2 and trace gases: 1%

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3
Q

Glycolysis makes

A

2 ATP, has no mitochondria involvement–> pyruvate and lactic acid result

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4
Q

Pyruvate and acetyl CoA combine to form

A

2 more ATP and CO2 production

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5
Q

Aerobic metabolism produces

A

34 ATP via the electron transport
utilizes O2
byproducts include: CO2, H20, and heat

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6
Q

The larynx consists of

A

9 cartilages
3 paired- corniculate, cuneiform, arytenoid
3 unpaired- epiglottis, thyroid, and cricoid

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7
Q

The nose is used for

A

filtration, smell, and humidification of incoming air

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8
Q

The airways consists of the

A

nose, mouth, pharynx, larynx, trachea, and lower airways

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9
Q

Sensory innervation to the larynx is via the

A

internal superior laryngeal nerve- vocal cords and above

recurrent laryngeal nerve- below the vocal cords

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10
Q

Motor innervation in the larynx is via the

A

recurrent laryngeal nerve to all but the cricothyroid muscle which is innervated by external superior laryngeal nerve

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11
Q

Abduction to the vocal cords is via the

A

posterior cricoarytenoid- please come apart

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12
Q

Adduction of the vocal cords is via the

A

lateral cricoarytenoid- “let’s close airway”

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13
Q

Tension to the vocal cords is via the

A

cricothyroid- “cords tense”

laryngospasm

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14
Q

Relaxation to the vocal cords is via the

A

thryoarytenoid- “they relax”

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15
Q

Describe the difference between the right and left bronchus is

A

the right main bronchus is shorter, wider, and more vertical (25 degree angle) than the left bronchus which is why a right mainstem intubation is more likely than a left
The left main bronchus has a 45 degree angle off the trachea

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16
Q

Where are the tracheal rings and what is the purpose

A

the tracheal rings sit anteriorly and prevent tracheal collapse

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17
Q

The role of the trachea and bronchi is to

A

transport gases between the atmosphere and the lung parenchyma

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18
Q

Describe the TLC in the left and right lungs:

A

the right lung makes up 55% TLC and is divided into 3 lobes

the left lung makes up 45% TLC and is divided into 2 lobes

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19
Q

The conducting zone is where

A

no gas exchange exists

goblet and mucous exist here

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20
Q

The transitional and respiratory zones are where

A

gas exchange occurs

absence of goblet cells

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21
Q

The diaphragm is the

A

primary muscle of ventilation

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22
Q

Innervation to the diaphragm comes from

A

C3, C4, and C5 nerve roots bilaterally to form the phrenic nerves

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23
Q

Internal intercostal muscles help with

A

forced expiration

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24
Q

External intercostals help with

A

forced inhalation

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25
Q

The lungs are made up of 3 types of pneumocytes:

A

Type 1- structural
Type 2- surfactant producing
Type 3- Macrophages (alveolar)

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26
Q

The surface area of the alveoli are

A

60-80 meters^2

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27
Q

The distance from the front incisors to the carina is approximately

A

26 cm
front incisors to larynx= 13 cm
larynx to carina= 13 cm

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28
Q

The respiratory zone consists of

A

the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli
gas exchange occurs here

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29
Q

The blood supply for the respiratory zones are from

A

the pulmonary circulation

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30
Q

Since respiratory bronchioles have a 0.5 mm diameter and smaller, gas flow is

A

so slow that gas moves more by diffusion rather than by bulk flow

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31
Q

The conducting zone is where

A

no gas exchange occurs

from the nose/mouth to the terminal bronchioles

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32
Q

The blood supply to the conducting zone is from the

A

thyroid, bronchial, and internal thoracic arteries (i.e. systemic circulation)

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33
Q

Terminal bronchioles measure

A

1 mm in diameter and lose cartilaginous plates

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34
Q

______ makes up the anatomic dead space

A

the conducting zone

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35
Q

Anatomic dead space can be estimated by any of the following:

A

150 mLs
1/3 the tidal volume
1 mL/lb or 2 mLs/kg of body weight

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36
Q

Describe how the respiratory cycle occurs

A

nerve impulse is sent to phrenic nerves and travels to the diaphragm
the diaphragm contracts and increases the superior-inferior dimension of the chest
external intercostal muscles help to lift the sternum and elevate the ribs increasing the A-P diameter
expiration is primarily a passive process
elastic forces in the lung, chest wall, and abdomen ehlp to compress the lungs
internal intercostals can help in forceful exhalation

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37
Q

Inspiratory muscles include

A

sternocleidomastoid, scalene

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38
Q

Expiratory muscles include

A

rectus, intenral/external obliques, transversus abdominus

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39
Q

The only time you could generate a positive intrathoracic pressure is during

A

forced expiration

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40
Q

The transpulmonary pressure is the

A

difference between the intrapleural and intra-alveolar pressures, and it determines the size of the lungs
A higher transpulmonary pressure corresponds to a larger lung

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41
Q

Work of breathing consists of

A

elastic and resistive work:
must overcome elastic and resistive forces of the lung and chest wall
work done to overcome airway resistance: can be natural or artificial airway devices and circuits

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42
Q

Neuronal control of the lungs is via the

A

brain stem by the medulla and pons

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43
Q

The medulla consists of the

A

dorsal respiratory group which stimulates inspiration- “Pacemaker for breathing”
the ventral respiratory group stimulations inspiration/expiration-helps with forced inspiration/expiration

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44
Q

The Pons control is via the

A

pneumotaxic center- decreases tidal volume for fine control of tidal volume - located high in the pons
the apneustic center- increases tidal volume for long and deep breathing
located lower in the pons

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45
Q

Output for the apneustic center is limited by

A

baroreflex input from the lung

input from the pneumotaxic center

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46
Q

The humoral control of breathing consists of:

A

the central and peripheral chemoreceptors that help regulate ventilation

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47
Q

The central chemoreceptors respond to

A

hydrogen ion levels

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48
Q

The peripheral chemoreceptors respond to

A

CO2, pH, and hypoxemia

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49
Q

The normal stimulus to breathe is

A

hypercapnia

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50
Q

Cranial nerve X- the vagus nerve carries the

A

aortic arch and lung stretch signals to the DRG

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51
Q

Cranial nerve IX- the glossopharyngeal carries the

A

carotid body signals to the DRG

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52
Q

Tidal volumes should be set to

A

6-8 mL/kg of IBW

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53
Q

Parasympathetic control of the airway comes from

A

the vagus nerve
causes mucus secretion, increased vascular permeability, vasodilation, and bronchospasm
bronchoconstriction is greatest in the upper airways

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54
Q

Activation of the M3 receptors results in

A

bronchoconstriction

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55
Q

Sympathetic control of the airway

A

has little input on tissues
inhibits mediator release from mast cells
increases mucociliary clearance

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56
Q

Activation of B2 receptors (exogenously) results in

A

bronchodilation

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57
Q

Lung volumes include

A

residual volume- cannot be measured with spirometry
expiratory reserve volume
tidal volume
inspiratory reserve volume

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58
Q

The capacities of the lungs include

A 
(made of 2 or more volumes)
Inspiratory capacity (IC= IRV +Vt)
vital capacity (VC= IRV+Vt+ERV)
Functional residual capacity (FRC= RV+ERV)
Total lung capacity (TLC= IRV+ Vt+ ERV+RV)
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59
Q

Inspiratory capacity is made up of

A

inspiratory reserve volume and tidal volume

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60
Q

vital capacity is made up of

A

inspiratory reserve volume, tidal volume, and expiratory reserve volumes

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61
Q

Functional residual capacity is made up of

A

residual volume and expiratory reserve volume

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62
Q

Total lung capacity is made up of

A

inspiratory reserve volume, tidal volume, expiratory reserve volume and residual volume

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63
Q

The respiratory quotient is

A

0.8

varies based on macronutrient metabolism

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64
Q

FRC represents the point where

A

elastic recoil force of the lung is in equilibrium with the elastic recoil of the chest wall

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65
Q

FRC represents the

A

“oxygen reserve”

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66
Q

Factors that affect FRC include

A

upright and prone position increase FRC
supine decreases FRC
muscle relaxation decreases FRC

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67
Q

Describe the pleuras in the lung

A

The lung is covered by the visceral pleura while the chest wall is covered by the parietal pleura

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68
Q

The space between the visceral pleura and the parietal pleura is known as the

A

pleural cavity

A small amount of serous fluid is maintained in this space to reduce friction

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69
Q

When air occupies the pleural cavity it is known as

A

the pneumothorax

70
Q

Air under pressure in the pleural cavity is known as

A

tension pneumothorax

71
Q

Blood in the pleural cavity is known as

A

hemothorax

72
Q

Excess serous fluid in the pleural cavity is known as

A

pleural effusion

73
Q

Empyema or pyothorax is

A

pus in the pleural cavity

74
Q

An organized blood clot in the pleural cavity is known as

A

fibrothorax

75
Q

Lymph in the parietal pleura is known as

A

chylothorax

76
Q

Compliance is a change in

A

volume divided by a change in pressure

77
Q

Static compliance is the compliance of

A

the lung and chest wall with NO AIR Movement

airway resistance doesn’t play a role in this calculation

78
Q

Reasons for decreased static compliance include

A

fibrosis, obesity, edema, vascular engorgement, ARDs, external compression, and atelectasis

79
Q

Static compliance can be calculated via

A

Cst= tidal volume/ (plateau pressure-PEEP)

normal value is 60-100 mL/ cmH2O

80
Q

To measure a plateau pressure, you have to set an

A

inspiratory pause on the ventilator. Most vents can only do this in volume control ventilation

81
Q

Dynamic compliance is the

A

compliance of lung and chest wall during a breath

airway resistance plays a large role in this calculation

82
Q

Reasons for decreased dynamic compliance include:

A

bronchospasm, tube kinking, mucous plugs, increased RR

anything that increases airway resistance!

83
Q

Dynamic compliance is calculated by

A

Cdyn= tidal volume/ (peak pressure- PEEP)

Normal value is 50-100 mL/cmH20

84
Q

What plays the largest role in reducing surface tension?

A

surfactant

it helps prevent atelectasis and small airway collapse

85
Q

Elastic forces are greatest in

A

collapsed and hyperinflated alveoli

this means they require a greater change in pressure to achieve a set increase in volume

86
Q

Laminar flow through the lungs is found mostly in

A

small airways

87
Q

Turbulent flow through the lungs is found mostly in

A

large airways

88
Q

The greatest airway resistance is in the

A

medium sized bronchi

89
Q

Reynolds number is used

A

to predict when flow will be laminar or turbulent

90
Q

A reynolds number of 2000 or below is indicative of

A

laminar flow

91
Q

A Reynold’s number of 4000 and above is indicative of

A

turbulent flow

92
Q

A Reynold’s number between 2000-4000 is considered

A

transitional flow

93
Q

Poiseuille’s law is used to determine

A

resistance to flow

radius is the most important factor in resistance to flow

94
Q

The West zones are

A

zones comparing alveolar pressure, arterial pressure, and venous pressure

95
Q

Zone 1 is where

A

Alveolar>arterial> venous pressure

V/Q= >1

96
Q

Zone 2 is where

A

Arterial>alveolar>venous pressure

V/Q=1

97
Q

Zone 3 is where

A

arterial>venous pressure>alveolar
V/Q= 0.8
Zone where the PA catheter tip should be placed
alveoli have the greatest compliance and perfusion

98
Q

Zone 4 is where

A

arterial>interstitial>venous pressure>alveolar V/Q <1

Zone 4 is a disease state

99
Q

The closing volume is the

A

volume above residual volume where small airways close

100
Q

Closing capacity is the

A

absolute volume of gas in the lung when small airways close (CV +RV)
increases from 30% of TLC at age 20 to 55% by age 70

101
Q

Closing volume is increased by

A

supine position, pregnancy, obesity, COPD, CHF, and aging

102
Q

If CV> FRC airway closure occurs during

A

tidal breathing causing poorly ventilated or under-ventilated alveoli and intrapulmonary shunting

103
Q

Oxygen in the blood is carried in two ways:

A

1-physical: dissolved in blood

2- chemical: bound to HGB (99.7% of O2)

104
Q

Dissolved oxygen is not

A

clinically significant

105
Q

Hemoglobin consists of:

A

4 protein subunits 2alpha and 2 beta chains
4 heme subunits
iron-porphyrin compound

106
Q

Each hemoglobin molecule binds up to

A

4 oxygen molecules

each gram of HGB binds 1.34 mL of oxygen

107
Q

The oxy-hemoglobin dissociation curve shows the

A

relationship between saturation of hemoglobin at a given plasma PO2

108
Q

A right shift of the oxy hemoglobin curve is

A

right release at the tissues

lower affinity for O2

109
Q

A left shift of the oxy hemoglobin curve is

A

left love- binds as much as it can because CO2 levels are lower
higher affinity

110
Q

A left shift of the oxy hemoglobin curve can be caused by

A

decreased temperature, decreased CO2- hypocapnia, increased pH- alkalosis, decreased 2,3 diphosphoglycerate

111
Q

A right shift of the oxyhemoglobin curve can be caused by

A

increased temperature, increased CO2- hypercapnia, decreased pH- acidosis, increased 2, 3 diphosphoglycerate

112
Q

The haldane effect is when

A

oxygenation of blood displaces carbon dioxide from hemoglobin
- this occurs at the A/C membrane of the lungs

113
Q

The Bohr effect is the

A

hemoglobin’s affinity for O2 is inversely related to CO2 levels
acidic environments cause a rightward shift- displaces O2 and allows CO2 to bind

114
Q

At a PaO2 of 27, SaO2 is

A

50%

115
Q

At a PaO2 of 40, SaO2 is

A

70%

116
Q

At a PaO2 of 60, SaO2 is

A

90%

117
Q

The DLCO tests the lungs

A

diffusing capacity for carbon monoxide (DLCO)

118
Q

Normal DLCO is

A

> 75% of predicted, up to 140%

119
Q

Mild DLCO is

A

60% to lower limit of normal

120
Q

Moderate DLCO is

A

40-60%

121
Q

Severe DLCO is

A

<40%

122
Q

DLCO is indicated in the evaluation of

A

parenchymal and non-parenchymal lung diseases in conjunction with spirometry

123
Q

CO2 can be transported in the blood via:

A

physical solution 5-10% (dissolved in blood)
chemically combined with amino acids of blood proteins 5-10% (bound to hemoglobin)
bicarbonate ions 80-90%- most CO2 is present in the blood as bicarb

124
Q

The carbonic anhydrase equation is

A

CO2 + H2O –> Carbonic anhydrase–> HCO3- + H+

assists rapid inter-conversion of carbon dioxide and water into carbonic acid, protons, and bicarbonate ions

125
Q

During the hamburger shift,

A

HCO2 leaves the RBCs and chloride enters to maintain electrical neutrality AKA “chloride shift”

126
Q

Acid-base balance is maintained through

A

serum buffers, the lung and kidneys work together to maintain a normal acid-base balance
serum buffers work continuously
lungs- minutes
kidneys- days

127
Q

Hypoxic hypoxia is a

A 
issue within the lungs
decrease of Fio2 (<0.21)
alveolar hypoventilation
V/Q mismatch
R to L shunt
supplemental O2 will help
128
Q

Clinical examples of hypoxic hypoxia include

A

high altitudes, O2 equipment error, drug OD, COPD, pulmonary fibrosis, PE, atelectasis, congenital heart disease

129
Q

Circulatory hypoxia is due to

A

reduced cardiac output

supplemental oxygen will have minimal effect

130
Q

Clinical examples of circulatory hypoxia include

A

severe heart failure, dehydration, sepsis, SIRS

131
Q

Hemic hypoxia is a

A

reduced hemoglobin content/function

supplemental O2 will have minimal effect

132
Q

Clinical examples of hemic hypoxia include

A

anemias, carboxyhemoglobinemia

methemoglobinemia- nitrate poisoning or prilocaine

133
Q

Demand/histotoxic hypoxia is due to

A

increased O2 consumption or inability to utilize O2

Supplemental O2 will help

134
Q

Clinical examples of demand hypoxia include

A

fever, seizures, cyanide toxicity

135
Q

Hypoxic pulmonary vasoconstriction is a

A

reflex contraction of pulmonary vasculature in response to a low regional partial pressure of oxygen

136
Q

HPV is intended to

A

match regional perfusion to ventilation in the lungs
diverts blood away from hypoxic areas of the lungs to areas with better ventilation and oxygenation (aims to correct V/Q mismatch)

137
Q

HPV is affected by

A

PAO2 levels, pH, PCO2, temperature

138
Q

the mechanism of action of HPV is

A

alterations in leukotrienes and prostaglandin synthesis

inhibition of NO production

139
Q

Increased PCO2 (acidosis) will lead to

A

vasoconstriction

140
Q

Decreased PCO2 will lead to

A

vasodilation

141
Q

In a hypoxic environment, it is important to note

A

pulmonary circulation vasoconstricts

142
Q

HPV is reduced or eliminated by:

A

elevated fiO2 & volatile agents above 1 MAC

143
Q

Causes of deadspace include

A

anything that causes decrease in pulmonary blood flow

pulmonary embolism, hypovolemia, cardiac arrest, shock

144
Q

Causes of shunts include

A

anything that causes the alveoli to collapse or fill

mucus plugging, ET tube in right or left mainstem, atelectasis, pneumonia, pulmonary edema

145
Q

Anatomical dead space is

A

air that is present in the airway that never reaches the alveoli and therefore never participates in gas exchange

146
Q

Alveolar dead space is

A

air found within the alveoli that are unable to function, such as those affected by disease or abnormal blood flow

147
Q

Physiologic dead space is equal to

A

anatomical dead space+ alveolar dead space

148
Q

Deadspace can be calculated via

A

Bohr’s equation

deadspace= Vt (PaCO2-PeCo2)/PaCO2

149
Q

PeCO2 is normally

A

2-5 mmHg less than PaCO2 due to mixing with anatomic dead-space during exhalation
increases with V/Q mismatch

150
Q

An absolute shunt is

A

V/Q= 0
hypoxia unresponsive to supplemental oxygen
everything that isn’t an absolute shunt is considered a V/Q mismatch

151
Q

Venous admixture is the reulut of

A

mixing of non-oxygenated blood with oxygenated blood distal to the alveoli

152
Q

mixed venous oxygen tension represents the

A

overall balance between O2 consumption (VO2) and O2 delivery (DO2)

153
Q

Factors that lower PVO2 include

A

decreased cardiac output
increased O2 consumption
decreased hemoglobin concentration

154
Q

Shunt like alveoli (low V/Q) have

A

low PO2 and high PCO2

think venous blood

155
Q

Deadspace-like alveoli have

A

high V/Q
high PO2 and low PCO2
think atmospheric air

156
Q

Symptoms of upper respiratory infection include

A

elevated WBCs, mucopurulent nasal secretions, inflamed and reddened mucosa, positive chest findings (ex. congestion, rales), temperature above 37 degrees Celcius, tonsillitis, viral ulcer in oropharynx, fatigue, laryngitis, sore throat

157
Q

Symptoms of allergy include

A

histamine mediated
sneezing, ash or boggy mucosa, itchy/runny nose, conjunctivitis, wheezing, hives, possible swollen lips, tongue, eyes or face, dry red and cracked skin

158
Q

Fick’s law of diffusion is

A

rate of gas diffusion= diffusion coefficient x surface area of the membrane x (difference in partial pressure/ thickness of the membrane)

159
Q

The alveolar gas equation states that

A

PAO2= (PB-PH2O) x Fio2- (PaCO2/0.8)
where PB= 760 mmHg
PH20= 47 mmHg

160
Q

Arterial oxygen content can be calculated by

A

CaO2= (HB x 1.34 x SaO2) + (PaO2 x 0.003)

161
Q

The alveolar-arterial oxygen tension gradient is

A

PAO2-PaO2
normal value is 5-15
Good indicator of overall gas exchange

162
Q

The A-a gradient increases with

A

age, obesity, supine position, and heavy exercise

-age leads to increased closing capacity and a decrease in PaO2

163
Q

Oxygen delivery can be calculated by

A 
DO2= QT x CaO2
QT= cardiac output
164
Q

Fick’s equation of oxygen consumption is

A

VO2= cardiac output x (CaO2-CvO2)

165
Q

CO2/alveolar ventilation can be calculated by

A

PaCO2= total CO2 production/alveolar ventilation

shows that PACO2 levels are inversely proportionate to alveolar ventilation

166
Q

The P/F ratio is found by

A

PaO2/FiO2

167
Q

A normal P/F ratio is

A

400-500

168
Q

A P/F ratio <300 indicates

A

mild ARDs

169
Q

A P/F ratio <200 is consistent with

A

moderate ARDs

170
Q

A P/F ratio <100 is consistent with

A

Severe ARDS

932 Pathophysiology (8 decks)

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